Thioester-isocyanides: versatile reagents for the synthesis of cycle-tail peptides.

A novel class of reagents, thioester isocyanides, have been prepared and applied in the synthesis of peptide macrocycles. The isocyanide part of the molecule is deployed in a multicomponent macrocyclization step. This step is followed by chemoselective peptide ligation at the thioester part of the macrocycle. Our method can now be used for rapid assembly and evaluation of cycle-tail peptides.